1. Field
The present invention relates to a chip resistor to be directly mounted on a wiring pattern of a printed wiring board by, for example, soldering. More specifically, the invention relates to a chip resistor of a multi-layered structure in which a plurality of resist elements and jumper wiring, etc. can be built in to be electrically independently from each other.
2. Description of the Related Art
Recent years, electronic devices are being further advanced in terms of downsizing, density and functions as can be seen in the field of mobile telephones, handy movie cameras, etc. In accordance with these advances, the wiring patterns of the printed wiring boards in which circuits with desired functions are becoming more dense and complicated. Therefore, there is a great demand for a multi-layered printed wiring board in which wiring lines can cross each other without coming into electrical contact with each other. However, multi-layered printed wiring boards with a number of layers are costly. Under the circumstances, there is further a demand for a single layer printed wiring board (or if not possible, a multi-layered printed wiring board with a least as possible number of layers) in which desired parts can be completely mounted.
In order to mount circuit parts on a single layer printed wiring board (or a surface print pattern of a multi-layered print pattern) at a high density, the pattern of such a printed wiring board is designed such that wiring lines pass between electrode leads of the circuit parts (such as resistors, capacitors, transistors and ICs) in many cases. In the case where the circuit pattern part does not allow such a design that lines are passed between electrode leads for some reason, jumper wires are employed. However, a jumper wire takes up an excessive area of the printed wiring board (, as compared to the case where a jumper wire is provided inside the laminated circuit board of a multi-layered printed wiring board), and therefore it is difficult to reduce the size or increase the density of the printed wiring board.
There has been provided a multi-electrode type resistor to be mounted on a surface of a circuit board, which enables crossing of circuits on a single-layer printed wiring board as in the above-described case where jumper wires are employed. (See Jpn. Pat. Appln. KOKAI Publication No. 2002-343614.) Further, as similar surface mount-type resistor, there are a double chip resistor (Jpn. Pat. Appln. KOKAI Publication No. 06-275411) and a double resistor chip (Jpn. Pat. Appln. KOKAI Publication No. 2000-030915).
The multi-electrode resistor disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2002-343614 has such a structure in which four resistors one end of each of which are electrically connected to each other are formed on a chip substrate and both ends of two pairs of resistor circuits (1a-1c and 1b-1d) are arranged to cross each other. (See FIG. 1 of this document.) When it is assumed that the above-described jumper wires are substituted with resistors, it is possible to make circuits cross each other on a single layer printed wiring board. This document further discloses a structure in which one of the two pairs of resistor circuits are replaced with jumper wires. (See FIG. 5 of this document.) In this case, it appears from the figure that circuits can cross each other on the single layer printed wiring board that uses the jumper wires.
In the double chip resistor disclosed in Jpn. Pat. Appln. KOKAI Publication No. 06-275411, two pairs of resistor circuits are arranged to cross each other on both surfaces of the chip board. (See FIGS. 1 and 2 of this document.) With this structure, the circuits can cross each other on the single layer printed wiring board that uses jumper wires.
One of the objects of the invention is to provide a chip resistor that can realize an electrically separated circuit crossing structure on a printed wiring board on which the circuits are mounted.